Referring to FIG. 1, conventionally, carrier Internet Protocol (IP) networks such as an exemplary network 100 are organized in tiers, where the lower tiers 102, 104, 106, 108 include edge routers 110 that connect to larger core routers 112. The edge routers 110 perform numerous IP protocol functions, whereas the core routers 112 are mostly called upon to forward traffic from one edge router 110 to another. Also, adjacent routers 110, 112 all support the same set of IP protocols. Currently, the lower layers supporting IP are treated as static IP links in order to avoid interference between the IP routing protocol and any dynamic reconfiguration of the lower layers, e.g. changes in the IP topology, may result in a need to reconverge the routing tables, causing an interruption in traffic. Further, the IP routers 110, 112 do not have the processing power to handle both the IP layer and lower layer topologies. As a result, multilayer control mechanisms such as Generalized Multi-Protocol Label Switching (GMPLS) (e.g., as defined by the Internet Engineering Task Force (IETF) in Requests for Comment (RFC) 3945, RFC 3471, RFC 3209, RFC 3479, etc., the contents of each are incorporated by reference herein) have not been deployed in practice in carrier IP networks.
The core router 112 is involved in the movement of any IP packets between edge routers 110, and as a result must handle very large amounts of traffic. Accordingly, the cost of core routers 112 is very high, however the actual use of IP protocols is relatively small since the core router 112 function is simply forwarding the packets between the actual packet source and destination. One option is to connect the edge routers 110 directly to one another, i.e. simply removing the core routers 112. However, directly connecting the edge routers 110 at an IP level results in a full mesh of connectivity between the edge routers 110, and introduces a significant penalty at the IP level to maintain adjacencies with every other edge router 110. Furthermore, interoperability of the routing protocols adds another constraint. Distributed IP routing protocols require that each router 110, 112 make the same routing decisions in order to avoid the creation of routing loops that could bring down the IP network 100. This creates a strong requirement that router software be interoperable and consistent, making it very difficult to introduce new functions or to allow a carrier to introduce a new IP vendor because of the risk of introducing routing problems.